The present invention is related to a hand tool, such as a wrench, with a swinging joint, the hand tool has a swinging joint permitting the head section of the tool to swing relative to the handle. The hand tool is equipped with a shift button for locking the swinging joint so as to fix the head section at a certain angle.
U.S. Pat. No. 7,000,507 (corresponding to Taiwanese Utility Model Patent No. M270888) discloses a hand tool having a swingable head section. The head section is fixable by a shift button. The rear end of the head section has a protruding pivot section. The front end of the handle has two lugs defining therebetween a recess. A slope is connected between the two lugs. The pivot section of the head section is positioned in the recess and pivotally connected with the two lugs via a shaft, whereby the head section can swing. A narrower side of the slope is spaced from the pivot section by a narrower distance, while a wider side of the slope is spaced from the pivot section by a wider distance. The shift button is laterally movably accommodated in the recess. A front end face of the shift button is formed with teeth for engaging with the teeth formed on a circumference of the pivot section. When the shift button is shifted to the narrower side as shown in FIG. 8 of the aforesaid patent, the shift button cannot be moved rearward, whereby the pivot section is kept engaged with the shift button to fix the head section at a certain angle. Reversely, when the shift button is shifted to the wider side as shown in FIG. 9 of the aforesaid patent, a space is reserved for the shift button to move rearward. Therefore, the shift button can be disengaged from the pivot section, permitting the head section to swing.
However, in the above structure, the slope can hardly reliably locate the shift button in the engaged position. This is because when the shift button is positioned in the engaged position as shown in FIG. 8 of the aforesaid patent, the rear end of the shift button abuts against the slope to keep the shift button engaged with the pivot section. In order to locate the shift button in the engaged position, the aforesaid patent employs a biasing unit for laterally pushing the shift button to prevent the shift button from sliding along the slope. However, the biasing unit provides a resilient force which can hardly sufficiently stops the shift button from moving. In the case that a greater force is applied to the head section to pivot the head section, the head section will exert a pushing force onto the shift button, which force is greater than the stopping force of the biasing unit. As a result, under such circumstance, the shift button will move along the slope toward the disengaged position as shown in FIG. 9 of the aforesaid patent. Therefore, the head section can be hardly truly fixed.
In addition, the rear end of the shift button of the aforesaid patent has a complicated structure and is hard to manufacture.